Effect of bar designs on peri implant tissues health in implant-supported removable prostheses: a systematic review.

Different characteristics of bars (cross-sectional shape, diameter, distal extension etc.) lead to different biomechanical behavior (retention and stress) with implants and peri-implant tissues.Aim: To evaluate the impact of implant-supported removable prostheses bar designs in fully edentulous arch (in the maxilla and/or mandibula), with 4 implants or more, on the peri-implant soft and hard tissues.Two reviewers searched for observational studies, RCT and in vitro studies, published on five main databases and three from the grey literature, without restrictions on November 2023.Of the 3049 selected articles, four met the inclusion criteria. Four RCT evaluated peri-implant health tissues in full edentulous arches with 4 or 6 implants rehabilitated with implant bar overdentures. One prospective study with 5 years follow-up evaluated the success/survival rate of implants and implant bar overdentures. Overall, 261 subjects were enrolled in our systematic review with 1176 implants. Overdentures' survival rate was 100%. There was a trend that plaque indices and gingival indices were low in all of the studies, however no statistical analysis was done due to the lack of information.Due to the lack of information in the included studies, we cannot confirm if bar characteristics affect the peri-implant tissues health.

Technical Report: Crown Fabrication Without an Impression.

Prosthetic treatment for elderly patients is a challenge that addresses both patient- and technology-mediated dental concerns. This report describes the fabrication of a cobalt-chromium crown without an impression using a digitized and scanned temporary crown to provide excellent integration.

Clinical Appraisal of the WAM'X Super Quick Post-and-Core Removal Device.

This report describes an innovative technique to remove post-and-core restorations. The WAM'X Super Quick post removal device permits a secure mechanical traction technique that can adapt to variable root angulations. Pivoting prongs mounted on forceps allow post removal while preserving the ferrule effect to improve resistance to fractures.

Effect of interface on surface morphology and proton conduction of polymer electrolyte thin films.

To understand the relationship between surface morphology and proton conduction of polymer electrolyte thin films, perfluorinated ionomer Nafion® thin films were prepared on different substrates such as glassy carbon (GC), hydrophilic-GC (H-GC), and platinum (Pt) as models for the ionomer film within a catalyst layer. Atomic force microscopy coupled with an electrochemical (e-AFM) technique revealed that proton conduction decreased with film thickness; an abrupt decrease in proton conductance was observed when the film thickness was less than ca. 10 nm on GC substrates in addition to a significant change in surface morphology. Furthermore, thin films prepared on H-GC substrates with UV-ozone treatment exhibited higher proton conduction than those on untreated GC substrates. However, Pt substrates exhibited proton conduction comparable to that of GCs for films thicker than 20 nm; a decrease in proton conduction was observed at ∼5 nm thick film but was still much higher than for carbon substrates. These results indicate that the number of active proton-conductive pathways and/or the connectivity of the proton path network changed with film thickness. The surface morphology of thinner films was significantly affected by the film/substrate interface and was fundamentally different from that of the bulk thick membrane.

Two-year clinical evaluation of three restorative materials in primary molars.

UNLABELLED: A variety of alternatives to amalgam are now available for use in Class I and Class II restorations in primary teeth, including glass ionomer cements, compomers and resin modified glass ionomer cements (RMGIC). OBJECTIVES: This study evaluated the two-year clinical performance of three restorative dental materials: A resin modified glass ionomer cement (Fuji IILC), a compomer (Dyract AP) and a high viscosity glass ionomer cement (Fuji IX), in primary molars of pediatric patients with high caries risk activity and compared these results to those reported for amalgam restorations. STUDY DESIGN: One hundred and forty nine Class I and Class II cavities in 45 patients aged 6 to 8 years were restored with compomer, glass ionomer cements and amalgam. Restorations were evaluated according to modified Ryge criteria by two examiners at baseline, and after 6, 12, 18 and 24 months of oral function. The data was submitted to statistical analysis (binomial and hyper geometric tests, p<0.05). RESULTS: Two-year recall rate was 62.42%. Class I performed better than class II restorations. The difference in marginal discoloration between compomer and amalgam restorations was statistically significant (p=0.014). No other significant differences were found between GIC, compomer and amalgam restorations. The clinical performance of the three restorative materials compared to amalgam in Class I and Class II cavities at two-year recall was acceptable. CONCLUSIONS: The results, even in a population with high caries risk activity, suggest that these materials are suitable alternatives to amalgam in Class I and Class II restorations in primary teeth.

Axial displacement of abutments into implants and implant replicas, with the tapered cone-screw internal connection, as a function of tightening torque.

PURPOSE: The passive fit of a superstructure on implant abutments is essential to success. One source of error when using a tapered cone-screw internal connection may be the difference between the tightening torque level applied to the abutments by the laboratory technician compared to that applied by the treating clinician. The purpose of this study was to measure the axial displacement of tapered cone-screw abutments into implants and their replicas as a function of the tightening torque level. MATERIALS AND METHODS: Twenty tapered cone-screw abutments were selected. Two groups were created: 10 abutments were secured into 10 implants, and 10 abutments were secured into 10 corresponding implant replicas. Each abutment was tightened in increasing increments of 5 Ncm, from 0 Ncm to 45 Ncm, with a torque controller. The length of each sample was measured repeatedly with an Electronic Digital Micrometer. The mean axial displacement for the implant group and the replica group was calculated. The data were analyzed by the Mann-Whitney and Spearman tests. RESULTS: For both groups, there was always an axial displacement of the abutment upon each incremental application of torque. The mean axial displacement values varied between 7 and 12 microm for the implant group and between 6 and 21 microm for the replica group at each 5-Ncm increment. From 0 to 45 Ncm, the total mean axial displacement values were 89 microm for the implant group and 122 microm for the replica group. CONCLUSION: There was a continuous axial displacement of the abutments into implants and implant replicas when the applied torque was raised from 0 to 45 Ncm. Torque applied above the level recommended by the manufacturer increased the difference in displacement between the two groups.

Structure and surface reactivity of novel nanoporous alumina fillers.

Recent studies have shown that the particle size of fillers used for the reinforcement of dental resin composites should be multimodally distributed, in which micron-sized fillers are mixed with nanoparticles so as to achieve a higher filler level in the resin, and should be kept well dispersed so as to be functionalized by a silane. In this study, porous alumina monoliths with high specific surface area, measured by the Brunauer-Emmett-Teller (BET) method, were obtained using a novel preparation method. Structure and surface reactivity have been investigated as functions of temperature and chemical treatments. The impregnation of the as-prepared material by triméthyletoxysilane (TMES) stabilized alumina with high specific surface area at higher temperature. FTIR study has described the effect of TMES treatment and temperature on the structure of the material. The use of allyldimethoxysilane (ADMS), as a probe molecule for measuring the surface reactivity, has allowed us to show that the treatment of samples with TMES and their reheating at 1300 degrees C results in adsorption sites which give stronger chemical bonds. This preliminary study has, therefore, allowed us to optimize the structural and surface treatment of experimental fillers before their use in the reinforcement of resin composites or resin-modified glass ionomer cements.

A comparison of methods of aesthetic assessment in root coverage procedures.

AIM: To evaluate the reliability of professional qualitative scoring methods used in evaluating aesthetic results after root coverage therapy and to evaluate the relationship between subjective and objective measurements. MATERIAL AND METHODS: A review panel of seven professional and non-professional, trained and untrained observers used photographic records to assess the overall cosmetic results of 162 root coverage surgical procedures in 133 patients (mean follow-up 17.51+/-17.37 months). Two different methods were used. In the before-after panel scoring system, observers evaluated the difference between preoperative and postoperative views, whereas in the random panel scoring system, observers rated each photograph independently. RESULTS: For both methods, intrarater agreement ranged from substantial to almost perfect for the periodontists. The best interrater agreement was found for trained periodontists using the five-point ordinal scale of the before-after panel scoring system (kappa=0.68). Neither root coverage percentage nor gingival augmentation was correlated to cosmetic assessment. CONCLUSIONS: The before-after scoring system is an acceptable and reliable method for professional cosmetic assessment of root coverage therapy. The overall cosmetic evaluation does not appear to be related to the percentage of root coverage.

Clinical evaluation of four different dental restorative materials: one-year results.

The purpose of the present study conducted in a school in Lebanon was to evaluate the one-year clinical performance of a polyacid-modified resin composite (PMC), a resin-modified glass ionomer cement (RMGIC), a high viscosity GIC (HVGIC) and an amalgam (Amlg). Hundred and forty-nine class I and class II cavities in 45 patients aged 6 to 8 years, with a high caries risk activity, were restored with these materials. Restorations were evaluated by two examiners at baseline, 6 and 12 months, according to USPHS criteria. Evaluation at 12 months showed that the retention of materials in class I and class II restorations in primary teeth was good. The recall rate was 97.4%. None of the restorations were clinically unacceptable, except for those with secondary caries (9/138). RMGIC gave the best results. At one year, RMGIC had the highest percentage of intact marginal integrity. Marginal discoloration in PMC restorations compared to Amlg restorations was statistically more important (p = 0.013). Secondary caries in HVGIC restorations, compared to Amlg restorations, were higher (p = 0.013). Clinical performance of the 3 restorative materials compared to Amlg in class I and class II cavities at one-year recall is not uniform. The results suggest that RMGIC is a suitable alternative to Amlg for restorations in primary teeth. Restrictions should be considered for the materials with more secondary caries (HVGIC) and higher marginal discoloration (PMC).

Adhesion between dental ceramic and bonding resin: quantitative evaluation by Vickers indenter methodology.

OBJECTIVES: The purpose of this study was to evaluate the adhesion to dental ceramic by Vickers indenter methodology. This technique allows the creation of adhesive fractures and determines the influence of the surface treatment on adhesive capacities. METHODS: A single bond adhesive system (One Step Bisco) was applied to ceramic Vitapan 3D Master CE 0124 samples. Ceramic samples were polished with 500 or 4000-grit paper, sandblasted or not (Sa/NSa), treated with fluorhydric acid or not (A/NA) and silane or not (Si/NSi). The experimental groups (Gr) were: (Gr 1) 4000; (Gr 2) 4000+Si; (Gr 3) 4000+Sa+A; (Gr 4) 4000+Sa+A+Si; (Gr 5) 500+Sa+A+Si. Each sample was indented with the diamond Vickers indenter Leitz Durimet 2 (Wetzlar, Germany) using a load of 20N for 30s. The surfaces of the debonded areas were observed in an optical microscope providing a digital image of the debonded surface. The adhesion bond strength was calculated according to the formula of Engel and Roshon [Engel PA, Roshon DD. Indentation-debonding of an adhered surface layer. J Adhesion 1979;10(33): 237-53]. The statistical analysis was conducted using Student's t test (p<0.05). RESULTS: The values obtained for each group were: (Gr 1) 32MPa; (Gr 2) 52MPa; (Gr 3) 112MPa; (Gr 4) 131MPa; (Gr 5) 265MPa. There is a significant improvement in bond strength with the silane application on the 4000 polished surface (Gr 2). However, there is no significant difference when silane is applied or not on a sanded and etched ceramic (Gr 4). Bond strengths were higher with 500 grit polished, sanded, etched with silane application on the surface (Gr 5). SIGNIFICANCE: The Vickers indenter methodology is able to discriminate between the influences of different surface treatments on the adhesion of an adhesive layer on a feldspathic ceramic.

Evolution of flexural rigidity according to the cross-sectional dimension of a superelastic nickel titanium orthodontic wire.

The choice of the most suitable orthodontic wire for each stage of treatment requires estimation of the forces generated. In theory, the selection of wire sequences should initially utilize a lower flexural rigidity; thus clinicians use smaller round cross-sectional dimension wires to generate lighter forces during the preliminary alignment stage. This assessment is true for conventional alloys, but not necessarily for superelastic nickel titanium (NiTi). In this case, the flexural rigidity dependence on cross-sectional dimension differs from the linear elasticity prediction because of the martensitic transformation process. It decreases with increasing deflection and this phenomenon is accentuated in the unloading process. This behaviour should lead us to consider differently the biomechanical approach to orthodontic treatment. The present study compared bending in 10 archwires made from NiTi orthodontics alloy of two cross-sectional dimensions. The results were based on microstructural and mechanical investigations. With conventional alloys, the flexural rigidity was constant for each wire and increased largely with the cross-sectional dimension for the same strain. With NiTi alloys, the flexural rigidity is not constant and the influence of size was not as important as it should be. This result can be explained by the non-constant elastic modulus during the martensite transformation process. Thus, in some cases, treatment can begin with full-size (rectangular) wires that nearly fill the bracket slot with a force application deemed to be physiologically desirable for tooth movement and compatible with patient comfort.

Effect of time on the flexural strength of glass ionomer and composite orthodontic adhesives.

The purpose of this study was to compare the effects of time on the flexural strength of a resin-reinforced glass ionomer and a composite adhesive system, specifically at three time frames corresponding to the three stages of polymerization of Fuji Ortho LC. Ten rectangular specimens of each material were prepared in a metal mold (25 x 2 x 2 mm) and then stored at 37 degrees C and 100% humidity in an incubator. Six test groups were created, in which each specimen was fractured using a 3-point-bending test at a crosshead speed of 0.5 mm/min. The test results indicated that there were significant differences among the groups (P = .0001). The flexural strengths were significantly higher in the two groups (III and VI) that were fractured after seven days. This was true for both the Fuji Ortho LC (x = 77 +/- 6.1 MPa) and the Concise (x = 103.9 +/- 4.2 MPa). The flexural strength of the resin-modified glass ionomer adhesive was significantly lower than that for the composite whatever the time of fracture, 10 minutes, one hour, or seven days. The analysis of the strength-deformation curve of the group of Fuji Ortho LC, which was fractured within 10 minutes after setting (group I), showed viscoplastic behavior, whereas that of all the others groups showed elastic behavior. According to this study, clinicians must consider the mechanics of Fuji Ortho LC setting and, when this material is used, wait for at least one hour to ligate initial or repaired arch wires.